International guidelines underline the utility to set a nutritional support whenever this is necessary, not only to prevent or treat malnutrition but also improve clinical outcomes. In this perspective, the improvement of oral diet and the use of oral nutritional supplements (ONS) represent the first-line strategy of intervention. Previous studies have shown that nutritional counseling, with or without the use of ONS, in patients with chronic disease is able to improve the calorie-protein intake, prevent deterioration of nutritional status, as well as to increase to a certain extent body weight. Particularly, energy-dense are more effective in increase energy intake. These data have highlighted the importance of a proper evaluation of the nutritional status of early detection of patients who could benefit of nutritional support. However, the independent role of the ONS in improving clinical outcome still needs to be established.